Synthetic polyamide compositions

ABSTRACT

A POLYAMIDE COMPOSITION WHICH CAN BE MELT SPUN OR SHAPED AND, IF NECESSARY DRAWN, WHICH COMPOSITION COMPRISES A CLASS OF PHENOLS WHICH CONFER INCREASED RESISTANCE TO DEFORMATION TO THE PRODUCT.

March 21, 1972 INITIAL MODULUS C. D. COWELL ET AL SYNTHETIC POLYAMIDECOMPOSITIONS Filed June 26, 1968 FIG] INITIAL MODULUS' vs EXTENSIBILITY.COMPARISON OF 6-6 NYLON AND MELT BLEND F 6-6 NYLON/COMPOUNDHI,(92/8I,COLD DRAWN YARNS.( BEFORE AND AFTER BOILING) 0 BEFORE BOILINGAFTER BOILING I I I I I I so EXTENSIBILITY o) MSLM Patented Mar. 21,1972 7 Claims ABSTRACT OF THE DISCLOSURE A polyamide composition whichcan be melt spun or shaped and, if necessary drawn, which compositioncomprises a class of phenols which confer increased resistance todeformation to the product.

The present invention relates to synthetic polyamide and co-polyamidecompositions for making shaped articles such as filaments, bristles,yarns, films and the like having improved resistance to deformation andalso to articles made therefrom.

The invention will be described particularly, but not limitatively, withreference to filaments, yarns and fabrics having improved resistance todeformation.

Synthetic polyamides, for instance nylon 6 or nylon 66, have long beenused for the manufacture of yarns and fabrics on account of theirdesirable properties such as good wear resistance and high strength.Such yarns or fabrics normally exhibit a floppy, pliable feel or easydrape and in some cases, such as curtains, this easy deformation orpliability is an advantage. In other cases, particularly in some areasof the garment field, yarns and fabrics are desirable which have moreresistance to deformation, than is obtainable with normal nylon yarnsand which, at the same time, exhibit the advantages of the good wearresistance and high strength associated with nylon.

One known way to increase the resistance to deformation of theconstituent filaments of a nylon fabric, is by tanning. Either themade-up fabric or the yarn used to make it may be treated for thispurpose in a bath containing a tanning agent such as tannic acid.Normally, however, the effect so obtained can be relatively easilyremoved almost completely by hot water or steam unless a further fixingtreatment, such as treatment with metallic salts, is performed.

In the preparation of synthetic polyamide or co-polyamide yarns themolten polymer is extruded through holes to form filaments, whichfilaments are usually then stretched or drawn in order to orientatetheir constituent molecules and develop their superior properties.

Treatment of undrawn or drawn filaments, or of yarns comprising them ina tanning bath is not only an undesirable extra operation but when suchfilaments or yarns are in the form of a wound package it is also almostimpossible to carry out in a practical manner owing to diificult anduneven penetration of the tanning agent into the package.

It is clearly desirable to be able to melt-spin synthetic polyamide orco-polyamide filaments in the normal manner, which filaments, aftersubsequent drawing, if necessary, have improved resistance todeformation at room temperatures. It is also desirable that suchimproved resistance to deformation should not easily be permanentlyremoved to any large extent by hot water or steam treatment.

Resistance to deformation of a filament may refer to resistance tostretching or to bending. Such resistance may be measured for instancein terms of a modulus. The stretch modulus can be defined by the forceper unit area to stretch the filament by a given percentage of itsoriginal length. The bending modulus or fiexural rigidity can be definedwith reference to the couple required to bend a filament of givendimensions through a given angle. With synthetic polyamide orco-polyamide filaments the bending modulus is generally positivelyrelated to the stretch modulus and so this latter property alone isusually used to define the general resistance of such a filament todeformation.

The stretch modulus can be measured in terms of any suitable stretchpercentage. In this specification We shall cite the 1% nominal modulus,usually called the Initial Modulus. The Initial Modulus is measured fora filament or yarn as follows:

A 50 cm. length of the filament or yarn is stretched at a rate of 10% ofits original length per minute on an Instron tester in a room atmosphereat approximately 67% RH. and 72 F. The tension in the yarn changes withthe degree of stretching and the two variables, length and tension, areautomatically plotted by the machine. The maximum tension-extensiongradient at the point where the stretch is approximately 1% ismultiplied by and divided by the initial yarn denier and the figure soobtained is called the Initial Modulus.

An object of the present invention is to provide a compositioncomprising one or more synthetic polyamides or co-polyamides, whichcompositions can be melt-spun or shaped and if necessary drawn toproduce filaments, bn'stles, yarns, films and the like having improvedresistance to deformation.

It is, of course, desirable that such filaments, yarns and the likeshould be capable of being deformed, such as crimped or bulked, by theprocesses conventionally employed therefor.

The compositions of the present invention may comprise one or moresynthetic polyamides or polyamide copolymers of a random or blocknature.

Clearly three important desiderata for the polyamide compositions of thepresent invention are: 1

(1) that they should be stable at elevated temperatures prior tomelt-spinning or shaping;

(2) that they should be capable of being melt-spun or shaped and, ifnecessary, drawn;

(3) that other properties of the articles produced therefrom, such asstrength, should be at least satisfactory and preferably improved.

Since many tanning agents, used in aqueous solutions are phenoliccompounds, such compounds were considered by applicants for addition tomolten polyamides. Furthermore, phenolic compounds are frequently addedin very small amounts to molten polyamides in order to reduce oxidativedegradation.

However, it is well known that some phenols, when added in appreciableamounts, may give rise to severe gelling of molten polyamides (forinstance simple phenol). At the same time, it has been taught that theaddition of phenolic compounds to molten polyamides, in amounts up toabout 40%, confers increased pliability on the articles made therefrom.Increased pliability is an effect exactly opposite to that desired inthe present context.

Applicants have now found, however, that there is a class of phenoliccompounds which compounds when admixed with molten polyamides orco-polyamides do not confer increased pliabiilty on the articles madetherefrom but, surprisingly, increase their resistance to deformation.

The phenolic compounds concerned in the present invention also have thesurprising advantage that mixtures of them with polyamides orco-polyamides in the molten state are sufiiciently thermally stable fornormal meltspinning or shaping to be performed, even when such mixturescontain a relatively high proportion of the phenol and articles soproduced can be drawn in the conventional manner to produce useful drawnarticles having improved resistance to deformation.

The phenolic compounds for use in the present invention aresubstantially pure, well defined chemical compounds with acharacteristic molecular weight, substantially ascertainable from theirchemical formula, and are not impure oligomers or mixtures of oligomersor polymers or resins. The phenolic compounds are selected from thegroup consisting of poly(alkyl) phenols, poly(hydroxyalkaryl) alkanesand poly(hydroxyalkaryl) arylenes. They are further defined as follows:

(a) they contain one or more benzene rings in the molecule,

(b) each benzene ring has not more than one hydroxyl group attachedthereto,

(c) at least one benzene ring has a single hydroxyl group attachedthereto,

(d) when the molecule contains less than four benzene rings the ringhydrogen atom at one or both ortho positions to each hydroxyl group issubstituted by a secondary or tertiary alkyl, including cyclo-alkyl,aryl or aralkyl group.

(e) the compounds should be soluble to an extent of l40 wt. percent inadmixture with one or more polyamides or co-polyamides.

The limiting desiderata determining the size and nature of anysubstituent groups, or the number of benzene rings, in the molecule arethe solubility of the compound in the polyamide or co-polyamide and theproduction of a composition which is sufiiciently thermally stable to bemeltspun or shaped, and, if necessary, drawn to produce articles havingincreased resistance to deformation.

Benzene rings in the phenol molecule may be linked together by anysuitable groups or chains, for instance methylene groups or chains, orsulphone or amide links and the like, consistent with the fulfilment ofaforesaid desiderata.

One or more such phenolic compounds should be present in the polyamidemixture for the accomplishing of the objects of the present invention,in a total amount between 2 and 20 Hydroxyl Equivalents per hundredAmide Equivalents and preferably between 3 and 10 such equivalents.

By Hydroxyl Equivalent we mean the molecular weight in grams of thephenolic compound divided by the number of hydroxyl groups in themolecule.

By the term hundred tAmide Equivalents we mean the molecular weight ingrams of a notional polyamide or copolyamide containing one hundredcarbonamide links.

Whilst phenolic compounds having one or two benzene rings in theirmolecule do exert an effect in increasing resistance to deformation, thepreferred phenols contain three or more benzene rings in their molecule.

The present invention therefore provides a composition comprising one ormore synthetic polyamides or co-polyamides, which composition can bemelt-spun or shaped and if necessary drawn to produce filaments,bristles, yarns, films and the like having improved resistance todeformation and which composition contains a phenol, which is asubstantially pure, well defined chemical compound with a characteristicmolecular weight, substantially ascertainable from its chemical formula,and is not an impure oligomer or a mixture of oligomers or a polymer orresin, is selected from the group consisting of poly (alkyl) phenols,poly(hydroxyalkaiyl) alkanes and poly (hydroxyalkaryl) arylenes and isfurther defined as follows:

(a) it contains one or more benzene rings in the molecule,

(b) each benzene ring has not more than one hydroxyl group attachedthereto,

(c) at least one benzene ring has a single hydroxyl group attachedthereto,

(d) when the molecule contains less than four benzene rings thering-hydrogen atom at one or both ortho positions to each hydroxyl groupis substituted by a secondary or tertiary alkyl, including cyclo-alkyl,aryl or aralkyl group.

(c) it should be soluble to an extent of l40 wt. percent in admixturewith one or more polyamides or co-polyamides,

either one or more such phenols being present in an amount between 2 and20 Hydroxyl Equivalents per hundred amide equivalents, said HydroxylEquivalents being defined as the molecular weight in grams of thephenolic compound divided by the number of hydroxyl groups in themolecule, and said Amide Equivalents being defined as the molecularweight in grams of a notional polyamide or co-polyamide containing onehundred carbonamide links.

The phenolic compounds may be added to the polyamide at any stage beforemelt-spinning or shaping. For instance, they may be added during themanufacture of the polyamide, preferably just before it is cast to makegranules for use in melt-spinning. Alternatively, they may be mixed withsaid granules or added to the molten polyamide in a melt-spinning orshaping apparatus.

Another convenient method of addiiton is to make granules comprising asuitable blend of one or more polyamides or co-polyamides and comprisinga high percentage of one or more of said compounds. Such concentrated,pre-blend granules can then be mixed, in suitable proportion, with thepolyamides or co-polyamides used for melt spinning or shaping.

Examples of the compounds used to produce compositions according to thepresent invention are shown in Table l.

The present invention will now be illustrated, but in no Way limited, bythe following practical examples:

EXAMPLE -1 Each of the compounds shown in Table l was dissolved inmolten nylon 66 by stirring for 15 mius. at 280 C., in a nitrogenatmosphere. The mixtures, containing 4% by weight of the compound, werecooled and the products melt-spun to produce spun yarns comprising tencontinuous filaments each of about nine denier. These yarns were thencold drawn and hot drawn under the conditions shown in Table 2. Both thespinning and drawing behaviour were good. The drawn yarns were thenimmersed in boiling water for 15 mius., dried in air at approximately67% RH. and 72 F. for 24 hours and their Initial Modulus, Extensibilityand Tenacity then measured.

The Tenacity is the breaking load of the yarn, expressed in grams perdenier. The Extensibility is the length by which the yarn can beextended before breaking, expressed as a percentage of its originallength. The Initial Modulus is as hereinbefore defined. The resultsobtained are shown in Table 2 as a function of the number of phenolichydroxyl groups in the molecule of the phenolic additive. It can be seenthat none of the compounds added produced any unacceptable change inExtensibility or Tenacity and that in general the Initial Modulusincreased with the number of hydroxyl groups in the molecule.

EXAMPLE 2 Polyamide compositions containing various amounts of CompoundIII (Table l) and prepared as described for Example 1 were melt-spun anddrawn to produce yarns which were tested as described hereinbefore. Theresults obtained are shown in Table 3. It can be seen from these resultsthat the Initial Modulus increases with the amount of additive withoutany serious change in the other properties. In all cases, of course,even in the absence of additive, boiling reduced the Initial Modulus aswell as altering the other properties, but with 10% additive present theInitial Modulus after boiling was as high or almost as high as the valuefor normal yarn before boiling.

TAB LE 2 (4% of compound in nylon 66) Number of phenolic groups inadditive EXAMPLE 3 5 molecule A mixture of 92 parts of Nylon 66 and 8parts of Com- 1 2 3 4 pound III (Table 1) was prepared as described forExam- Yam properties after boiling; pie 1 and melt-spun to form yarn.Th1s yarn was cold z g fi g t pe adrawn at different draw ratios toproduce yarn of different ?M M8 18.9 2M 25 3 25 2 extensibilities. Therelationship between the Initial Mod- 10 gg z fi s p c n 36.7 33.2 30.030.6 30.5 plus and Extensibility, for both boiled and unhoiled yarn,Dravtgn d ad-Data's?" M1 1s shown 1n FIG. 1. It can be seen that themodulus- 18(1) i B 21 2 6 O t q ea effect of the additive is present atall the Extenaxtsn sibiiit'gf'oaiijj 25:6 3116 331i 311% iii s b l t esTenacity, g./d 6. 70 6. 91 7. 6. 33 6. 21

EXAMPLES 4-28 Further polyamide and copolyamide compositions wereprepared containing various amounts of various phenols of the presentinvention. Such compositions were spun and drawn to produceapproximately 130 denier 5 filament yarns having extensibilities lyingbetween approximately 30 and 45.

The drawn yarns were bo1led and then" Inltlal Modulus TABLE 3 measuredas described hereinbefore. The said compose tions together with theirextensibilities and initlal modull OH equwsper 100 CONH e(1111177- areshown in the following Table 4. In general, as yarn is 0 1.3 2.6 3.9 5.46.9 drawn to a higher draw ratio its extenslblllty decreases Percentcompound In 0 2 4 6 8 and its 1n1t1a1 modulus lncreases. In order toapprec1ate D t the increased moduli of the yarns produced from thecomg??? f temperature positions according to the present 1nvent1on asshown in I.M.],3gi/d.:b H Table 4 such moduli should be compared withthe modulus g% ffi 1 i g 33.1 4 corresponding to the same extensibilityfor poly 1P 16 9 16 G 20 1 0 p e or 01 in taming no phenol add1t1ve(e.g. as 1n FIG. 1). After boilingg 2&2 3&6 3H 3.3 28':

Tenacity, g./d.: TABLE 1 Before boiling 6. 04 6 as 6.05 5.80 5. 72 Afterboiling." 5.01 5 01 5.22 5.01 5.23 No, of Drawn over hotplate atCompound: Chemical name ffi gf-f 1 2,4 dimethyl-G-t-butyl phenol.lgfetforeabciiling- 0.2; 39 48.0 51.3 61.4 62.4 I or 01 mg l. 7 27. 724. 3 28. 8 34.5 11 22 -methylene b1s (4 methyl 6t butyl Extensibilitypercent:

phenol). Before boiling 13.3 12.2 12.2 11.9 11.0 12.9 1111 1,1,3 tri[(2methyl-4-hydroxy-5t.butyl)- 410 g efig m 25.6 26.1 24.6 26.0 24.2 26.7phenyl] butane. Before bgiiiling 7.80 7. 59 8.26 7. 30 7.61 7. 46 IV1,1,5,5 tetra[(2 methyl-4 hydroxy-St.bu- After 5. 5. 88

tyl)phenyl] pentane.

TABLE 4 Additive Concentration Hydroxyl equivs. Properties of drawn peryarn (alter boiling) hundred Polyamide or 00- Percent amide Extensi-Initia Example N0. polyamide Phenolicaddltwe byweight equivs. bilitymodnlu 4 nylon 66 Dimethyl Bisphenol A (methyl groups ortho to hydroxylgroups) 8 7.7 41 1 d Tetramethyl Bisphenol A (methyl groups ortho tohydroxyl groups) 8 6. 9 38 21 2,2-di (4-hydroxy-3-metl1ylphenyl)-propane8.0 7. 7 41.1 17. 8 2,2,-di-(4-hydroxy-3,5-d1methyl phenyl)-propane- 8.06.9 37.7 21.3 2,2-di-(4-hydroxy-3,5-di1sopropylpheny1) propane 8. 7 5. 536. 7 23. 0 1,1,32-tri(4 hydroxy-3,5-d1methyl-phenyl)-butane 6. 3 5. 437. 3 31. 9 2,2,5,5-tetra(4-hydroxy-3,5-dimethy1phenyl) -hexane 5. 9 5.037. 0 26. 2 1, 4-bis(di(B-tert-butyl-4-hydroxy-2-methyl phenyl)(methy1)benzene 8.3 5. 5 38. 7 24. 8 1,1,3 tri((2methyl-4-hydr0Xy-5-tertbutyDphenyl) butane 8 5. 43 38 29 do 0 0 10 do s 5.4 45 13 nylon 11 do 00 44 22 rin do s 8.7 44 a2 MXD/nylon 6"--. do 0 0 30 56 do do s 5.9 3161 Product of reaction between following phenolic acids and diaminesPhenolic acid Diamine acid 19 nylon 66 2-hydroxy-p-toluic acidp-phenlyene-diamine 7.7 5.0 41.3 25.4 20 rin do m-phenylenediamine 7.75.0 39.7 24.2 21 do do p-Amino cyclo hexylmethane 9. 6 5.0 33.8 28. 0 22do 3,3-d1(4-hydroxy-phenyDvaleric p-phenylene-diamine 6.7 5.0 31.8 28.4

acid (diphenolic acid). 23 do do m-Phenylcne-diamine 6. 7 5. 0 29. 2 32.6 24 do do 4,4 diamino-di-phenylmethane. 7. 5 5. 0 34.1 26. 3 25 do dom-Xylylene diamine 6.9 5.0 44.8 27. 2 26 do3,3d1(4-hydroxy13,5-dlmethy1- p-Pheny1ene diamlne 7.7 5.0 40. 6 25.1

phenyl) -va1erlc acid(tetramethyi-diphenolic acid). 27 do do m-Phenylenediamine 7. 7 5.0 43.1 33. 3 23 do d p-Amino cyclohexylmethane 8. 7 5.033.6 24. 1

What we claim is:

1. A thermally, stable fiber-formable composition comprising a syntheticlinear, fiber-formable polyamide having improved resistance todeformation containing an amount sufficient to improve said resistanceto deformation of a phenol, said phenol being a substantially purewell-defined chemical compound with a characteristic molecular weightsubstantially ascertainable from its chemical formula, said phenol beingselected from the group consisting of poly(alkyl)phenols,poly(hydroxyalkaryl) alkanes, poly(hydroxyalkaryl) arylenes, said phenolbeing further defined as follows:

(a) it contains one or more benzene rings in the molecule,

(b) at least one benzene ring has a single hydroxyl group attachedthereto,

() when the molecule contains less than four benzene rings the ringhydrogen atom at one or both ortho position to each hydroxyl group issubstituted by a secondary or tertiary alkyl, including cyclo-alkyl,aryl or aralkyl group,

(d) it is soluble to an extent of 1-40 wt. percent in admixtures withsaid polyamide,

said phenol being present in said composition in an amount between 2 andhydroxyl equivalents per hundred amide equivalents, said hydroxylequivalents being defined as the molecular weight in grams of thephenolic compound divided by the number of hydroxyl groups in themolecule, and said amide hundred equivalents being defined as themolecular weight in grams of a notional polyamide or copolyamidecontaining one hundred carbonamide links.

2. A composition as claimed in claim 1 wherein said amount is between 3and 10 hydroxyl equivalents per one hundred amide equivalents.

3. A composition as claimed in claim 1 'wherein said polyamide ispolyhexamethylene adipamide.

4. A composition as claimed in claim 1 wherein said phenol contains 3 ormore benzene rings.

5. The composition of claim 1 wherein said phenol contains 1 to 4benzene rings which are each substituted by a single hydroxyl group.

6. A composition as claimed in claim 4 wherein said phenol contains 3 ormore benzene rings.

7. The composition of claim 5 wherein said phenol contains only onephenol selected from the group consisting of 2,4,6-trialkyl phenol;2,2-bis alkylene(4,6-dialkyl phenol); 1,1,3-tri[ (2,5-dialkyl-4hydroxy)phenol]butane; 1,1,5,5- tetra[ (2,5 dialkyl4-hydr0xy)phenol]pentane; o-dialkyl bis-phenol A;2,2-di(4-hydroxy-3-alkyl phenyl) propane; 2,2,5 ,5 -tetra(4-hydroxy-3,5-dialkyl phenyl)hexane and 1,4- bis di5-alkyl-4-hydr0xy-2-alkylphenyl] alkyl) benzene.

References Cited UNITED STATES PATENTS 3,009,900 11/1961 Hansen et al26045.7 3,445,408 5/1969 Gabris 26045.95 3,086,960 4/1963 Bletso26045.95 2,996,466 8/1961 Kessler et a1. 26045.95

HOSEA E. TAYLOR, Examiner W. E. PARKER, Assistant Examiner csmmcmt 9FCQRECTQN Patent Not 3,651,010 Dated March 21. 1972 Inventofls) C.D.Cowell et a1 It is certified that error appears in the above-identifiedpatent and that said Letters Patent are hereby corrected as shown below:

IN THE SPECIFICATION Column 4, line 14, "20" should read "10" Column 4,line 43, subsequent to the numeral "66' insert the phrase --orpolyhexamethylene adipamide" Table 4 Under heading "Initial Modulus"; "1should read "18" IN THE CLAIMS Claim 4 should read:

4. A composition as claimed in claim 1 wherein said phenol contains 2 to6 benzene rings.

' Signed and sealed thisZZnd d OfFAugUSt 1972.

(SEAL) attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSGHALK Attesting Officer Commissionerof Patents

